The described invention relates in general to a sonotrode system, assembly, and device for use in various ultrasonic applications, and more specifically to a modified sonotrode assembly for use in package sealing applications and other applications that provides enhanced performance and extended life over prior art sonotrodes of a similar nature.
A sonotrode for use in ultrasonically sealing packages is disclosed in U.S. Pat. No. 9,205,596, which is incorporated by reference herein, in its entirety, for all purposes. With reference to FIGS. 3, 7, and 9 presented herein, the disclosed sonotrode includes a body with nodal and anti-nodal regions that is configured to propagate ultrasonic waves received at a nodal region along a first direction; a plurality of redirecting features (e.g., slots) formed in the body and configured to cause received ultrasonic waves propagating along the first direction to propagate along a second direction that is perpendicular to the first direction upon encountering one or more of the redirecting features; wherein the body is further configured to stretch and compress along the second direction based on corresponding peaks and valleys of the waves propagating along the second direction; and at least one ultrasonic welding surface located at an anti-nodal region of the body, wherein the at least one ultrasonic welding surface is configured to oscillate based on the stretching and compressing.
With regard to the sonotrode disclosed in U.S. Pat. No. 9,205,596 and with reference to FIGS. 3, 7, and 9 herein, the sonotrode body includes an elongated structure having anti-nodal regions along the long sides of the elongated structure and nodal regions along the short sides, of the elongated structure. Opposing ends of the sonotrode comprise the nodal regions and at least one of the opposing ends is configured to receive the ultrasonic waves. The redirecting features include elongated slots passing through the material of the body and extending along the second direction. In some embodiments, the elongated slots are substantially equally spaced across the body and include substantially equal widths across each slot and varying lengths along each slot. In some embodiments, the length of the elongated slots closer to the ends of the body are greater than the lengths of the elongated slots further from the ends of the body (i.e., closer to the center of the body). The thickness of the body is tapered along the second direction from a center portion of the body, extending along the first direction, to the edges of the body. The edges of the body each comprise anti-nodal regions having substantially uniform thickness along their lengths, and at least one of the anti-nodal regions comprises the at least one welding surface. The center portion of the body includes a uniform thickness along the first direction, the tapering extending from the center portion of uniform thickness to the edges.
The sonotrode disclosed in U.S. Pat. No. 9,205,596 is specifically designed for a transversely aligned ultrasonic transducer and is intended for use in rotary ultrasonic systems for sealing packages such as those used to contain food products and other items. This prior art sonotrode is effective for its intended purpose; however, the device exhibits a relatively short lifespan and after approximately four hours of operation, fractures form in the sonotrode nodal region where an ultrasonic input tool (e.g. a booster or a transducer) connects to the sonotrode during normal use. After such fractures are observed, the package sealing system must be stopped and the sonotrode must be replaced. Frequent replacement of these sonotrodes slows production time and results in significant expense. Accordingly, there is a need for a sonotrode that can be used with rotary ultrasonic systems for sealing packages and the like that is more durable and that exhibits a significantly longer lifespan than prior art sonotrodes of a similar nature.